December weather forecast and climate
Sweet Grass, MT

The first month of the winter, December, is also a subzero cold month in Sweet Grass, Montana, with average temperature fluctuating between 27.1°F (-2.7°C) and 15.3°F (-9.3°C).

Temperature

The coldest month is December, with an average high-temperature of 27.1°F (-2.7°C) and an average low-temperature of 15.3°F (-9.3°C).

Humidity

The average relative humidity in December is 77%.

Rainfall

In Sweet Grass, in December, during 3.5 rainfall days, 0.43" (11mm) of precipitation is typically accumulated. Throughout the year, there are 70.4 rainfall days, and 8.46" (215mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall. In December, in Sweet Grass, it is snowing for 10.2 days. Throughout December, 2.72" (69mm) of snow is accumulated. Throughout the year, there are 54.3 snowfall days, and 19.49" (495mm) of snow is accumulated.

Daylight

The month with the shortest days in Sweet Grass is December, with an average of 8.3h of daylight.

Sunshine

Months with the least sunshine are January and December, with an average of 5.6h of sunshine.

UV index

January through March, October through December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index value of 2, and less, symbolizes a low health risk from unprotected exposure to the Sun's UV rays for the average person.
Note: In December, the average maximum UV index of 2 translate into the following recommendations:
Extended sun exposure is not an issue for the majority. Children, infants, and fair-skinned individuals always need to be protected. The Sun's most intense and consequently most harmful UV radiation during midday hours should be decreased by minimizing exposure and seeking shade. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the coldest month in Sweet Grass?

December is the coldest month in Sweet Grass, Montana, with an average high-temperature of 27.1°F (-2.7°C) and an average low-temperature of 15.3°F (-9.3°C).

What is the temperature in December in Sweet Grass?

In December, in Sweet Grass, the average high-temperature is 27.1°F (-2.7°C), and the average low-temperature is 15.3°F (-9.3°C).

What is the average humidity in December in Sweet Grass?

The average relative humidity in December in Sweet Grass, Montana, is 77%.

How many days does it rain in December in Sweet Grass?

In Sweet Grass, Montana, in December, during 3.5 rainfall days, 0.43" (11mm) of precipitation is typically accumulated.

How many days does it snow in December in Sweet Grass?

In Sweet Grass, Montana, in December, during 10.2 snowfall days, 2.72" (69mm) of snow is typically accumulated.

What is the month with the shortest days in Sweet Grass?

With an average of 8.3h of daylight, December has the shortest days of the year in Sweet Grass, Montana.

What is the average length of the day in December in Sweet Grass?

The average length of the day in December in Sweet Grass is 8.3h.

What is the month with the least sunshine in Sweet Grass?

January and December, with an average of 5.6h of sunshine, are months with the least sunshine.

How many hours of sunshine does Sweet Grass have in December?

The average sunshine in December in Sweet Grass, Montana, is 5.6h.

What is the month with the lowest UV index in Sweet Grass?

Months with the lowest UV index are January through March, October through December, with an average maximum UV index of 2.

What is the UV index intensity in December in Sweet Grass?

The average daily maximum UV index in December is 2. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to the UV radiation.
Average temperature in December - Sweet Grass, MT
  • Average high temperature in December: -2.7°C

The warmest month (with the highest average high temperature) is July (26°C).
The month with the lowest average high temperature is December (-2.7°C).

  • Average low temperature in December: -9.3°C

The month with the highest average low temperature is August (12.9°C).
The coldest month (with the lowest average low temperature) is December (-9.3°C).

Average pressure in December - Sweet Grass, MT
  • Average pressure in December: 1020mbar

The month with the highest atmospheric pressure is January (1020.3mbar).
The month with the lowest atmospheric pressure is June (1011.5mbar).

Average wind speed in December - Sweet Grass, MT
  • Average wind speed in December: 18.3km/h

The windiest month (with the highest average wind speed) is January (19km/h).
The calmest month (with the lowest average wind speed) is August (14.1km/h).

Average humidity in December - Sweet Grass, MT
  • Average humidity in December: 77%

The month with the highest relative humidity is January (79%).
The month with the lowest relative humidity is August (43%).

Average rainfall in December - Sweet Grass, MT
  • Average rainfall in December: 11mm

The wettest month (with the highest rainfall) is June (45mm).
The driest month (with the least rainfall) is July (8mm).

Average rainfall days in December - Sweet Grass, MT
  • Average rainfall days in December: 3.5 days

The month with the highest number of rainy days is May (10.4 days).
The month with the least rainy days is November (2.6 days).

Average snowfall in December - Sweet Grass, MT
  • Average snowfall in December: 69mm

The month with the highest snowfall is February (91mm).
Months with the least snowfall are June, July and August (0mm).

Average snowfall days in December - Sweet Grass, MT
  • Average snowfall days in December: 10.2 days

The month with the highest number of snowfall days is December (10.2 days).
Months with the least snowfall days are July and August (0 days).

Average daylight in December / Average sunshine in December - Sweet Grass, MT
  • Average daylight in December: 8.3h

The month with the longest days is June (Average daylight: 16.1h).
The month with the shortest days is December (Average daylight: 8.3h).

  • Average sunshine in December: 5.6h

The month with the most sunshine is July (Average sunshine: 12h).
Months with the least sunshine are January and December (Average sunshine: 5.6).

Average sunshine days in December - Sweet Grass, MT
  • Average sunshine days in December: 19.5 days

The month with the most sunshine days is July (23.5 days).
The month with the least sunshine days is April (17.4 days).

Average UV index in December - Sweet Grass, MT
  • Average UV index in December: 2

The month with the highest UV index is July (UV index 6).
Months with the lowest UV index are January, February, March, October, November and December (UV index 2).

Average cloud cover in December - Sweet Grass, MT
  • Average cloud cover in December: 40

The month with the most cloud cover is February (Cloud cover 43).
The month with the least cloud cover is July (Cloud cover 15).

Average visibility in December - Sweet Grass, MT
  • Average visibility in December: 9km

Months with the highest visibility are May, June, July, August, September and October (10km).
Months with the lowest visibility are January, February, March, April, November and December (9km).